Also called post-fire debris flows, these mudslides form when water rushing down slopes picks up dirt, burnt trees, rocks, and other debris (like cars), reaching speeds of more than 35 miles per hour. “When you mix a lot of mud, water, and boulders, it certainly can be quite catastrophic,” says Dennis Staley, a scientist with the US Geological Survey Landslide Hazards Program. The slurries can start with almost no warning after as little as a third of an inch of rain in just 30 minutes — especially on slopes scorched by fires. After fires blazed across more than half a million acres this fall in California’s worst fire season on record, it’s not hard to find burnt land.

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The information in this blog is compiled by Point Blue President & CEO, Ellie Cohen, from science news outlets from around the world. It does not necessarily reflect the views of Point Blue or our staff.